With his hunched back and deformed face, Quasimodo, the tragic hero of Victor Hugo's novel "The Hunchback of Notre Dame," has always been considered a mythical creation drawn from the depths of the author's imagination.

But clues suggesting that Quasimodo is based on a historical figure have been uncovered in the memoirs of Henry Sibson, a 19th-century British sculptor who was employed at the cathedral at around the time the book was written and who describes a hunched back stonemason also working there.